Roller mills include a pair of cooperating corrugated rolls that operate at different speeds to crack or grind material, such as high moisture grain. The grain is fed through a discharge opening in a hopper to the rolls which are mounted within a closed housing.
The typical roller mill has included a mechanism for varying the spacing between the rolls to regulate the degree of grain cracking or processing. To provide an adjustment of spacing, one of the rolls is fixed in position, while the shaft of the other roll is journalled within a pair of bearing assemblies that are mounted for sliding movement with respect to the housing. A rod is secured to each bearing assembly and is threadedly engaged with a shaft which carries a drive sprocket. By rotating the drive sprockets in unison, the shafts will be rotated to thereby move the bearing assemblies and the movable roll relative to the fixed roll. With the adjusting mechanism, as used in the past, a compression spring was mounted around the rod and was seated between a nut threaded on the rod and the housing. The spring biased the movable roll toward the fixed roll and yet was yieldable so that if an enlarged object passed between the rolls, the movable roll would move outwardly to accommodate the enlargement. With the adjusting system as used in the past, rotation of the sprockets to vary the spacing was done manually and due to the substantial force exerted by the springs, rotation of the sprockets through an operating handle was difficult and required substantial force, meaning that the operator would normally have to apply a wrench or pipe to the operating handle in order to produce sufficient leverage to rotate the sprockets against the force of the springs.
As a further disadvantage, the adjusting mechanisms as used in the past, varied the spring force with the adjustment of the rolls, meaning that as the spacing between the rolls was increased, the springs would be further compressed, thereby increasing the spring force. This meant that the force necessary to release the roll to accommodate an enlargement varied with the spacing between rolls.
Roller mills, as used in the past, have also included a mechanism for varying the effective area of the discharge opening in the hopper. The discharge opening is normally enclosed by a sliding gate which is spring biased to a closed position and can be moved to an open position through a manually operated pull rod. A collar associated with the pull rod is adapted to engage an adjustable stop to regulate the effective size of the discharge opening and thereby control the flow of grain to the rolls. With the roller mills as used in the past, the stop has consisted of a series of fingers mounted on a rotatable shaft, and by rotating the shaft through a manual control, the fingers could be selectively positioned to be engaged by the stop to thereby limit the movement of the pull rod and vary the size of the discharge opening. With mechanisms of this type as used in the past, the stop fingers were positioned at various intervals along the length of the rod and there was no infinite adjustment of the effective area of the discharge opening.